Field of the Invention
The present invention relates to a dispersant suitable for dispersion of various insoluble coloring materials (hereinafter, also referred to simply as “coloring material”) such as pigments and oil-soluble dyes, a compound constituting the dispersant, and further a toner using the dispersant.
Description of the Related Art
Conventionally, coloring materials are dispersed in media such as solvents and resins (hereinafter, also referred to simply as “medium”), and are used as inks, coating materials and toners. In such applications, since it is needed that a coloring material is dispersed homogeneously in a medium, a dispersant such as a dispersant or a surfactant is generally concurrently used. Usual dispersants for coloring materials are constituted of an “adsorption site” having adsorbability to the coloring materials and a “dispersion site” having affinity for media. Since the each site can be designed so as to be adapted to the coloring materials and the media, various dispersants have been developed and reported so far.
As means to enhance adsorbability to coloring materials, dispersants whose adsorption sites have structures analogous to the coloring materials are proposed. Japanese Patent Application Laid-Open No. 2003-081948 proposes a low molecular compound containing a benzimidazolinone skeleton, which is purported to be improved in the adsorption power to a coloring material by introducing the same structure as that of the coloring material to the adsorption site. Further Japanese Patent Application Laid-Open No. 2003-238837 proposes a polymeric compound obtained by polymerizing a monomer containing a benzimidazolinone skeleton. Further Japanese Patent Application Laid-Open No. 2009-501253 proposes a polymer grafted with a site concurrently intramolecularly having a benzimidazolinone skeleton and an azo group. Further U.S. Pat. No. 7,582,152 discloses, as a dispersant for a coloring material for inkjet recording, an example of a polymer dispersant in which a chromophore whose molecular weight is lower than 95% of that of an azo pigment is bonded to a water-soluble polymer main chain. Further Japanese Patent No. 3984840 discloses a polymer pigment dispersant in which an azo or disazo chromophore containing a substitution product of acetoacetoanilides is bonded to a polymer.